1. Field of the Invention
The present invention relates to an apparatus for keeping an optimal penetration depth formed at the front end of an oxygen tuyere and a method for keeping the same when producing molten pig iron utilizing non-coking coal, and more particularly to an apparatus for keeping an optimal penetration depth formed at the front end of an oxygen tuyere and a method for keeping the same using a sensor for measuring distance which is installed at the inside of oxygen tuyere when producing molten pig iron utilizing non-coking coal.
2. Description of the Prior Art
Generally, a blast furnace method, which forms the majority of the producing facilities of molten pig iron, requires raw material having a strength above a certain degree because of the characteristic of a reactor. As a carbon source used as a fuel and a reducing agent, coke obtained by processing a coking coal, is used. Accordingly, the producing facilities of the coke should be necessarily accompanied. In addition, the exhaustion of the raw coal of the coke and the regulation of various environment contaminating materials generated during the production of the coke has rapidly decreased the competitive power of the blast furnace method.
To cope with the above-mentioned circumstance, world nations have accelerate the development of production method of molten pig iron, which utilize the non-coking coal as the fuel and the reducing agent. U.S. Pat. No. 4,978,387 discloses the conventional production facilities of the molten pig iron using the non-coking coal.
According to U.S. Pat. No. 4,978,387, energy required for various processes is supplied through the combustion of a coal bed while injecting oxygen through a plurality of tuyeres, formed at the outer wall of the compacting layer with a constant distance in a circular shape, into the inner lower portion of the coal packed bed formed at a melter gasifier with a predetermined height. At this time, since the volumetric flow rate and the pressure of the oxygen injected through the tuyere are quite large and intensive, a space formed toward the inner portion of the coal packed bed (i.e. a penetration depth) is inevitably formed in front of the tuyere. The penetration depth largely affects the utilizing efficiency of the combustion energy, which is the supply source of the required energy in the production facilities of the molten pig iron utilizing the noncoking coal. Therefore, too short or too long penetration depth forms the gas as an excessive circumferential flow or an excessive central flow in the coal packed bed to deteriorate the effective use of the combustion energy.
Accordingly, an optimal keeping of the penetration depth is very important in the operation of the production facilities of the molten pig iron utilizing the non-coking coal. The optimal penetration depth is kept by keeping the oxygen blowing velocity at the tuyere constant by controlling the pressure applied in the melter gasifier according to the volume of the oxygen blown through the tuyere, for the present.
However, the penetration depth formed in the coal packed bed is under the influence of the structure, the particle size and the density of the coal which forms the coal packed bed, as well as the oxygen blowing velocity at the tuyere. Hence, even though the oxygen blowing velocity is kept constant, the optimal keeping of the penetration depth according to the change of various conditions of the raw material, is difficult.